cleanup unused method

src/Services/Identity/Identity.API/Program.cs

@@ -71,24 +71,3 @@ finally
 {
     Serilog.Log.CloseAndFlush();
 }
-
-IConfiguration GetConfiguration()
-{
-    var builder = new ConfigurationBuilder()
-        .SetBasePath(Directory.GetCurrentDirectory())
-        .AddJsonFile("appsettings.json", optional: false, reloadOnChange: true)
-        .AddEnvironmentVariables();
-
-    var config = builder.Build();
-
-    if (config.GetValue<bool>("UseVault", false))
-    {
-        TokenCredential credential = new ClientSecretCredential(
-            config["Vault:TenantId"],
-            config["Vault:ClientId"],
-            config["Vault:ClientSecret"]);
-        builder.AddAzureKeyVault(new Uri($"https://{config["Vault:Name"]}.vault.azure.net/"), credential);
-    }
-
-    return builder.Build();
-}